LPL is essential for alveolar macrophage podosome formation. (A) Alveolar macrophages from adult WT mice were applied to glass coverslips and fixed. F-actin was illuminated by staining with phalloidin-AlexaFluor 488 (green), and LPL was labeled with anti-LPL mAb followed by DyLight594 (red). LPL colocalizes with F-actin in podosomes (white arrows). Scale bar shows 20 μM. (B) Confocal image analysis demonstrating podosome formation in alveolar macrophages from adult WT animals (white arrow) with a podosome defined as an actin dot (green) surrounded by anti-vinculin staining (red). Podosomes did not form well, if at all, in alveolar macrophages from adult LPL^−/− mice (yellow arrow). Scale bar shows 5 μM. (C) Percentage of alveolar macrophages with podosomes from adult WT (gray bar) or LPL^−/− (black bar) mice. Data from 3 independent experiments combined; the standard errors of the mean of the proportions are shown and were calculated using the formula standard error = √(p*(1 − p)/n), where p represents proportion and n represents the number of samples; P value was determined using Fisher’s exact test.